#include <bits/stdc++.h>
using namespace std;
int main() {
    int in;
    long long l = 1, r = 1e9;
    long long mid = (1e9 + 1) / 2;
    printf("%lld\n", mid);
    fflush(stdout);
    scanf("%d", &in);
    while (in != 0) {
        if (in == -1) {
            l = mid + 1;
            mid = (l + r) / 2;
            printf("%lld\n", mid);
            fflush(stdout);
            scanf("%d", &in);
        } else {
            r = mid;
            mid = (l + r) / 2;
            printf("%lld\n", mid);
            fflush(stdout);
            scanf("%d", &in);
        }
    }
    return 0;
}